The project 200 zygotes, how many meiotic divisions are required in flowering spermatocytes ?

Options

A. 125
B. 250
C. 300
D. 400

Answer

To solve the problem of how many meiotic divisions are required to produce 200 zygotes in flowering plants, we can break it down into a series of logical steps:

### Step-by-Step Solution:

1. **Understanding Zygote Formation**:
- A zygote is formed by the fusion of a male gamete (sperm) and a female gamete (egg). Therefore, to produce 200 zygotes, we need 200 male gametes and 200 female gametes.

2. **Male Gamete Production**:
- Male gametes in flowering plants are produced through a process called microsporogenesis.
- During microsporogenesis, a microspore mother cell undergoes meiosis (a reductional division) to produce four haploid microspores (male gametes).
- Thus, from one meiotic division, 4 male gametes are produced.

3. **Calculating Meiotic Divisions for Male Gametes**:
- To find out how many meiotic divisions are needed to produce 200 male gametes, we use the formula:
\[ \text{Number of meiotic divisions} = \frac{\text{Total male gametes}}{\text{Male gametes produced per division}} = \frac{200}{4} = 50 \]
- Therefore, 50 meiotic divisions are required to produce 200 male gametes.

4. **Female Gamete Production**:
- Female gametes are produced in the ovary from a megaspore mother cell, which also undergoes meiosis.
- However, from one meiotic division of the megaspore mother cell, only one functional egg is produced, while the other three cells degenerate.

5. **Calculating Meiotic Divisions for Female Gametes**:
- Since we need 200 female gametes (eggs) for 200 zygotes, the number of meiotic divisions required is:
\[ \text{Number of meiotic divisions} = 200 \text{ (one for each egg)} \]

6. **Total Meiotic Divisions**:
- Now, we add the meiotic divisions required for both male and female gametes:
\[ \text{Total meiotic divisions} = \text{Meiotic divisions for male gametes} + \text{Meiotic divisions for female gametes} = 50 + 200 = 250 \]

### Final Answer:
The total number of meiotic divisions required to produce 200 zygotes is **250**.